The present invention relates generally to a new engine for use in, for example, personal watercraft. In particular, the present invention relates to a new four-stroke in-line engine that was developed with a view to the future stricter environmental and emission regulations. The engine has a blow-by ventilation system for separating lubricant that may be entrained within blow-by gases. The engine further includes an improved lubrication system.
There is a very popular type of watercraft known as a xe2x80x9cpersonal watercraftxe2x80x9d which is designed to be operated primarily by a single rider. Although this type of watercraft is commonly employed for single riders, frequently provisions are made for accommodating additional passengers although the maximum number of passengers is more limited than conventional types of watercraft.
This type of watercraft is also generally quite sporting in nature and normally accommodates at least the rider on a type of seat in which the rider sits in a straddle fashion. The passenger""s area is frequently open through the rear of the watercraft so as to facilitate entry and exit of the rider and passengers to the body of water in which the watercraft is operating, as this type of watercraft is normally ridden with passengers that are wearing swimming suits.
These personal watercraft are generally quite small so that they can be conveniently transported from the owner""s home to a body of water for its use. Because of the small size, the layout of the components is extremely critical, and this gives rise to several design considerations that are peculiar to this type of watercraft. However, due to its sporting nature, it is also desirable that the watercraft be powered by an engine and propulsion device that is not only efficient but also generates sufficient power.
Traditionally, two-cycle engines have been used to power watercraft, including personal watercraft. These engines have the advantage that they are fairly powerful, relatively lightweight, and compact.
One particular disadvantage to the two-cycle engine is its emission content. Two-cycle engines generally exhaust larger quantities of hydrocarbons and other pollutants than four-cycle engines due to cylinder charging inefficiencies and the combustion of lubricating oil among other things. When measures are taken to reduce emissions of the two-cycle engine, other generally undesirable consequences can result, such as an increase in the weight of the engine, a reduction of its power output or the like. With concern for the environment and increasingly strict emissions requirements being instituted by various governing bodies There is motivation to provide a power plant that reduces exhaust emissions while retaining other advantageous characteristics such as compactness, low weight and high power output.
Four-cycle engines are commonly used as power plants in other applications, such as automobiles. These engines have the advantage that their emissions output are generally desirably lower as compared to a two-cycle engine for a given power output.
It is an object of the present invention to provide a four stroke, in-line engine having a compact construction.
It is another object of the present invention to provide a four stroke, in-line engine having a modular construction to permit the interchange of parts between various engine models.
It is another object of the present invention to provide a four stroke, in-line engine having improved exhaust emission characteristics.
It is another object of the present invention to provide a four stroke engine having a narrow and low profile.
It is another object of the present invention to provide a four stroke engine having a low profile valve actuation assembly for controlling the operation of the intake and exhaust valves.
It is another object of the present invention to provide a cylinder head having a low profile to reduce engine height.
It is another object of the present invention to offset the placement of the intake valves and exhaust valves with respect to a vertical axis within the cylinder head to reduce engine height.
It is another object of the present invention to provide an improved spark plug mounting assembly for easy access within the cylinder.
It is another object of the present invention to provide a Y-shaped intake rocker arm assembly for easy access within the cylinder.
It is yet another object of the present invention to provide a four stroke engine having an improved oil collection system and oil holding tank.
It is another object to provide a four stroke engine which combines a closed loop cooling system and an open loop cooling system for enhanced cooling of the engine in accordance with the present invention.
It is another object to provide an open loop cooling system for cooling an exhaust manifold in accordance with the present invention, wherein the open loop cooling system enhances cooling of the crankcase and cylinder head.
It is another object to provide an open loop cooling system for cooling an exhaust manifold in accordance with the present invention, wherein the open cooling system lowers the temperature of the exhaust manifold such that the exhaust manifold functions as a heat sink for the crankcase and cylinder head.
It is another object of the present invention to provide a closed loop cooling system for selectively cooling the crankcase and cylinder head of the four stroke engine.
It is another object of the present invention to provide a closed loop cooling system having a selectively operable heat exchanger.
It is another object of the present invention to provide a supercharger for enhanced engine performance.
The present invention is directed to a four stroke internal combustion engine having an improved lubrication system and system for separating lubricant from blow-by gas within the crank case. The present invention is also directed to a personal watercraft having the same. The engine includes a crankcase, and a cylinder head connected to the crankcase, which together form at least one cylinder. The crankcase includes at least one crank chamber located below the cylinder. A crankshaft is rotatably mounted within the crankcase and extends through each crank chamber. The engine further includes intake valves and exhaust valves associated with each cylinder. A valve actuation assembly located in the cylinder head for operating the valves.
The engine further includes a lubrication tank formed in the crankcase. The lubrication tank includes a lower portion located beneath the crank chamber and an upper portion extending upwardly along one side of the crankcase. A balance shaft is rotatably mounted within the crankcase. The balance shaft extends parallel to the crankshaft through the upper portion of the lubrication tank. A baffle may be provided in the upper portion of the lubrication tank to cover a portion of the balance shaft.
The crankshaft and the balance shaft extend from the crankcase into a power take off housing located on one end of the crankcase. A rotating member is secured to the crankshaft within the power take off housing. The rotating member is operatively coupled within the power take off housing to the balance shaft.
The power take off housing includes a lubricant collection portion formed in a lower portion the power take off housing. A first lubricant pump is located within the power take off housing. The lubricant pump is operatively connected to the balance shaft. A lubricant transfer passageway extends from one end of the crankcase adjacent the power take off housing to an opposite end of crankcase. The lubricant transfer passageway is operatively connected to a lubricant sieve. The lubricant sieve may be connected to a second lubricant pump. The second lubricant transfer passageway extends from the second lubricant pump to the lubrication tank. The power take off housing includes an integrally formed oil filter housing. The oil filter includes a drainage port located within the oil filter housing. The drainage port is opened when the oil filter cover is removed from the oil filter housing. A fastening rod secures an oil filter cover to the oil filter housing. The drainage port is opened when the fastening rod is removed. Associated with the oil filter is a by-pass circuit that is operatively connected to the oil filter. The by-pass circuit is operational when the oil filter is dirty.
A cylinder piston is slidably mounted within the cylinder and separates the chamber from the crank chamber. A lubricant nozzle may located within the crank chamber beneath the cylinder piston, which directs a stream of lubricant on the cylinder piston such that the lubricant cools the cylinder piston during operation.
The crank chamber includes a lubrication drainage aperture formed in a lower portion of the crank chamber. Lubricant and blow-by gas exits the crank chamber through the lubrication drainage aperture into the upper portion of the lubrication tank. A drainage passageway extends from each lubrication drainage aperture. The drainage passageway is connected to a main drainage passageway, which is connected to the upper portion of the lubrication tank. The main drainage passageway extends upwardly along a side of the upper portion of the lubrication tank.
The lubrication tank includes a venting passageway for venting blow-by gas containing lubricant. The engine further includes a lubricant separator operatively connected to the venting passageway. The lubricant separator includes a separation chamber for separating lubricant from the blow-by gas, a lubricant outlet located at a lower portion of the separation chamber for draining lubricant from the separation chamber, and a gas outlet located at an upper portion of the separation chamber for exhausting gas from the separation chamber. The separation chamber has a generally conical shape.
The lubricant outlet may be operatively connected to a lubricant seive. The lubricant seive is connected to a lubricant pump. A lubricant transfer passageway extends from the lubricant pump to the lubrication tank.
An exhaust passageway extends from the gas outlet. A first valve is located within the exhaust passageway and is selectively operable to close the exhaust passageway during predetermined operating conditions. A solenoid actuator controls the operation of the first valve during the predetermined operating conditions.
A second valve may be located in the venting passageway. The first valve and the second valve are operatively connected such that the second valve closes the venting passageway when the first valve closes the exhaust passageway. The solenoid actuator controls the operation of both valves during predetermined operating conditions.
In accordance with a preferred form of the present invention, the venting passageway separates the blow-by gas into a first stream and a second stream. The first stream is directed into the cylinder head. The second stream is directed to the lubricant separator operatively connected to the venting passageway.
The engine in accordance with the present invention includes a first lubricating passageway extending within the crankcase from the lubrication tank to the cylinder head. A lubrication circuit is located within the cylinder head and is operatively connected to the first lubricating passageway. A check valve is located within the first lubricating passageway to block the flow of lubricant into the lubrication circuit when the engine is not operating. A throttle may positioned within the first lubricating passageway to control the amount of lubricant entering the lubrication circuit from the first lubricating passageway. The lubrication circuit may include a transverse passageway fluidly connected to the first lubricating passageway, at least one connecting bore extending from the transverse passageway within the cylinder head, andat least one cylinder head bore. The cylinder head bore is adapted to receive a cylinder head fastener. The lubricant within the lubrication circuit travels around the cylinder head fastener.
A support shaft is rotatably mounted within the cylinder head. The valve actuation assembly includes a cam shaft operatively coupled to at least one exhaust rocker arm for operating the exhaust valves. The cam shaft is also operatively coupled to at least one intake rocker arm for operating the intake valves. Each of the exhaust rocker arms and the intake rocker arms is rotatably mounted on the support shaft.
The lubrication circuit may further include a connecting passageway extending from the cylinder head bore to a central passageway formed in the support shaft. Lubricant flows through the central passageway into the rocker arms.